Lola - Ke55 4a-gze

[love ke70]

maybe its sticky linkages somewhere?

gearbox off is probably an engine out job?

[ancullen]

In light of the issues I've had with the GT-Four, I've decided that I want the KE55 ready to race again. And I want it to be FAST!!! I'm not overly concerned about the handling though. What I'm thinking about doing is building the engine up, and eventually buying a kit car of some kind (eg. PRB Clubman) and putting the 4A-GZE in it. That way I lose weight, and gain IRS and adjustable suspension. :)

 

With this in mind, I've been searching for parts. I am looking at buying the following in the next week or so:

 

276-degree, 9.89mm lift cams (should give powerband of about 4,500-8,500rpm)

Double valve springs

 

I will also be on the look out for a replacement igition coil.

 

Next I will be testing the tailshaft to see if it needs fixing or if it is okay. Hopefully it's just a matter of bolting it back up to the diff and it's all fine.

 

With the ignition coil and the tailshaft in place, the car will again be driveable. The other parts I'm purchasing will be set aside will I build up the full collection of parts needed. Other bits include:

 

0.5mm metal head gasket

Adjustable cam gears

1SZ-FE single-piece shims/buckets

Titanium valve spring retainers

Undersize crank & supercharger pulleys, lightweight water pump pulley, oversize lightweight alternator pulley

BIG valves - standard are 29.5mm intake & 25.5mm exhaust. I'm trying to decide if 32mm intake and 27.5mm exhaust are big enough (and are only $150), or if I must have the 33.5mm intake and 28mm exhaust valves I've discovered (at $330). Need to talk to the people that will be building my engine first. :D

 

With the modifications I have planned, including the ABV mod and a serious retuning of the ECU (redline will go to 9,000rpm), I hope to be making over 140kW at the wheels. Only time will tell though.

[love ke70]

the smaller valves will do, its not all about size :)

[ancullen]

But I figure that with a bigport head with a mild port and polish (mostly just a clean up), I may as well take full advantage of the extra flow and get the biggest valves possible. :)

[Pure-SX]

Sounds good? Who will you be getting to build the engine?

[ancullen]

I'm thinking JNL for the engine build, and Hi-Tech for the tuning.

[Pure-SX]

Was thinking the same thing, have only heard good things about JNL.

[Hiro Protagonist]

So what ended up being the problem with the GT4?

[ancullen]

Still working on fixing the GT-Four... :)

 

I'm going to be buying a master & slave cylinder rebuild kit, as well as a longer slave cylinder rod from the US. Apparently (amongst other things) GT-Four's have issues with clutch engagement/disengagement with aftermarket clutches (which mine has). One of the solutions is this longer rod, which if I'm rebuilding/replacing the slave cylinder anyway, I may as well install.

[love ke70]

But I figure that with a bigport head with a mild port and polish (mostly just a clean up), I may as well take full advantage of the extra flow and get the biggest valves possible. :)

 

id talk to your engine builder before doing this, biggest valves are not always going to make the best power....especially at the modest figures you are aiming at..

[ancullen]

140kW at the wheels is modest??? On a 4A-GZE!?!?! Remember I'm not going turbo here. I'm going for 9,000rpm and will need as much flow as possible. I will probably end up buying the smaller valves though, simply for economical reasons.

 

But at least I know where I can source bigger valves if/when I need them. :)

[love ke70]

it has to do with port velocity.

remember, the supercharger is going to be your limiting factor. you can build everything else to flow 700hp, but when your superdupercharger only flows 200hp, thats all your gonna make, and your gonna be doing it the hard way with everything else built beyond that.

a valve size that will flow 700 hp or whatever will not flow 200 hp very well. if I'm making sense...

cheers

[Trev]

it has to do with port velocity.

remember, the supercharger is going to be your limiting factor. you can build everything else to flow 700hp, but when your superdupercharger only flows 200hp, thats all your gonna make, and your gonna be doing it the hard way with everything else built beyond that.

a valve size that will flow 700 hp or whatever will not flow 200 hp very well. if I'm making sense...

cheers

I can see where Andrew is coming from, It would probably be like putting a SC12 onto a 20 valve.

[ancullen]

I've just had a realisation dawn on me about the 4A-GZE and the SC12. I can't believe it's taken me this long.

 

With standard AE101 pulleys (150mm crank, 120mm supercharger):

At 7,500rpm, the 1.6L 4A-GZE can draw in up to 12,000L of air per minute.

At 9,375rpm (1.25 times engine speed), the SC12 can supply up to 11,250L of air per minute.

Therefore at 7,500rpm (engine speed), there is a shortfall of 750L of air per minute. There is a constant shortfall in air volume supplied vs. air drawn in by the engine, and the greater the engine rpm, the greater the variance.

 

With aftermarket crank pulley (175mm crank, 120mm supercharger):

At 7,500rpm, the 1.6L 4A-GZE can draw in up to 12,000L of air per minute.

At 10,312.5rpm (1.375 times engine speed), the slightly altered SC12 can supply up to 12,375L of air per minute.

Therefore with the larger crank pulley, at 7,500rpm (engine speed), the SC12 can now supply an excess 375L of air to the engine. Now instead of an ever increasing shortfall, there is instead an increasing surplus. I'm not suggesting that this would make the 4A-GZE able to rev infinitely, but with the right cams and other head work, it should allow the engine to rev better.

 

This realisation is extremely important, as my 4A-GZE would have been creating a shortfall of 900L of air per minute at 9,000rpm. Now I need to rethink my pulley situation - not a big deal, just something that needs addressing.

 

Thanks to both Andrew and Trev for helping me come to this realisation, however indirectly you did it. I was actually responding to your comments on flow when I came to this realisation. And to now get to that:

 

Andrew - the valves I'm looking at are designed for the 4A-GE, so although they are quite large, they obviously work on other tuned 4A-GE's - I'm just applying them to a tuned 4A-GZE instead.

 

Trev - BIG thanks for making me think about the SC12 a bit more. I can't find much on 4A-GZE 20v's being built. I know there's at least one in existance - I've seen a picture, but that's it. I've also seen a picture of a 4A-GZE 16v with 20v quad throttles. They fit nicely. :)

Edited October 1, 2007 by ancullen

[Trev]

Trev - I've only ever found evidence of one 4A-GZE 20v being built, and that was just a picture. Unfortunately I couldn't find any dyno graphs or comments on how the engine worked. I've also seen an image of a 4A-GZE with quad throttles from a 20v. No one has yet given a definitive answer on how well such a setup works. I want to see how well a high revving 4A-GZE works.

 

In the words of NickZ about the SC 20v:

 

Seen it done, but ran out of power after about 6000, as i just can't supply the volume of air the engine needs, in the end made the car slower, Just go with a 4agze to begin with